Partners in Water Quality Monitoring at Mammoth Cave National Park, Kentucky

Water resources are essential to landscape development and maintenance of the extraordinary ecosystem at Mammoth Cave National Park, Kentucky. The National Park Service has implemented many policies and management practices in an eff ort to maintain and improve the water quality in the park. As part of their resources management, the Park evaluates current hydrologic conditions, as well as, anticipates and responds to emerging issues. With regards to that goal, Mammoth Cave National Park Service partnered with Tennessee State University, the Mammoth Cave International Center for Science and Learning, and the U.S. Geological Survey on a series of water-related projects from 2007-2013. The objective of this paper is to highlight some of the fi ndings and lessons learned from the past 6 years. Many of the results presented in this paper have been presented at other conferences or published in other reports. Collaborative projects included storm-water runoff from parking lots and roads, evaluating storm-water fi lters, and transport of chemicals in the caves. These projects purposefully engaged students to provide professional experience and educational outreach opportunities. Over 50 student presentations related to these monitoring activities have been made at regional and national conferences in the past 6 years, resulting in numerous awards and publications. Major funding or in-kind services were provided by the partnering agencies and institutions. Additional funding for supplies and student support was provided by the National Science Foundation (Opportunity for Enhancing Diversity in Geoscience, 2007-8; Undergraduate Research and Mentoring, 2009-13), and, the Department of Energy (Massey Chair – NNSA, 2007-13). The following summaries are excerpts from previously published student papers (West et al., 2010; Diehl et al., 2012, Embry, et al., 2012, West et al., 2012). Evaluating parking lot storm-water fi lters There were two phases to the parking lot fi lter evaluation. The fi rst evaluation took place seven years after the fi lters had been installed, prior to and after servicing the fi lter systems. The second phase occurred two years later, preand post-maintenance. The parking lot storm fi lter systems use an oil and grit separator followed by fi lters fi lled with cartridges containing zeoliteperlite-activated carbon granules. The fi lter systems vary in size, depending on the size of the parking lots. The fi lters are designed to trap suspended particles and dissolved constituents, such as metals and oils, as runoff fl ows through the fi lter units. The manufacturer suggests swapping fi lter cartridges every 2 years (Figure 1). The fi rst phase project (West, et al., 2010) was conducted to determine if leaf-pack fi lter-systems attenuated storm runoff at seven parking lots in Mammoth Cave National Park. Grab samples were collected at the inlet and outlet of the fi lter systems, and analyzed for oil and grease, sediments, turbidity, gasoline compounds, nitrate, 178 Mammoth Cave National Park's 10th Research Symposium: Celebrating the Diversity of Research in the Mammoth Cave Region ammonia, fecal bacteria, dissolved iron, and chemical oxygen demand (Figure 2). For the fi rst sampling round, the fi lters had not been serviced for 8 years and did very little to remove contaminants. The contaminant concentrations at the outlet were similar to those at the inlet, with the exception of removing 20-70 percent of the oil and grease. After replacing the cartridge fi lters and cleaning debris out of the oil-grit separators, the re-conditioned fi lters did little to remove copper and ammonia from runoff waters. However, the re-conditioned fi lters removed up-to 99% of the benzene, toluene, ethyl-benzene and xylene, and, up to 90% of the turbidity, E. coli, Chemical Oxygen Demand and iron from the storm runoff . These results indicate that wellmaintained fi ltration systems are more eff ective than clogged fi lters at removing many but not all contaminants from parking lot runoff . The second phase (Diehl, et al., 2012) evaluated storm-water fi lters that had been serviced 2 years prior. The study focused on the fi rst runoff waters during the storms (Figure 3). The fi lters were eff ective at removing petroleum aromatic ring compounds, but were less eff ective at removing zinc and copper. Regression analysis established a correlation between decreasing fi lter effi ciency for copper with increasing parking lot size. Also, there was a positive correlation between increasing parking lot size and increasing copper concentration in the runoff . Quaternary ammonia compounds (QACs) are a new concern because of their use in White Nose Syndrome disinfection stations and in RV sanitation tanks. The fi lters that received the highest QAC concentrations during storm runoff were eff ective at reducing 4090% of the QAC concentrations. Additional work is continuing to determine if new cartridge fi lters improve the effi cacy of the storm-water fi lter systems. Transport of Chemicals into the caves (West, et al., 2012, Embry et al., 2012) In 2011, the National Park Service began deliberations concerning the application Figure 1: Contractors serviced the stormwater fi lters by swapping the cartridges. (Hotel-east shown here) Figure 2: TSU students prepared water samples and ran chemical analyses. Mammoth Cave National Park's 10th Research Symposium: Celebrating the Diversity of Research in the Mammoth Cave Region 179 of road deicers on primary roads through the Park. However, the NPS lacked some essential quantitative information with regards to contaminant transport from land surface into the cave ecosystem. The objective of this investigation was to characterize storm fl ow from potential source areas on the surface into the cave. The preliminary results were achieved by monitoring water chemistry and bacteria near source areas, along the surface fl owpaths, and along known fl owpaths in the cave (Figure 4). A quantitative tracer study found it took one hour for dye to move from land surface, along the main fl owpath, and into the cave (Figure 5). Constituents, such as quaternary ammonia compounds (QACs), chemical oxygen demand, ammonia, and diesel range aromatic ring compounds, decreased exponentially along the fl owpath, to below detection levels in the cave. Zinc, copper, and nitrate decreased along the surface, but Figure 3: TSU student setting up a monitoring station at the storm-fi lter outlet. then held steady at low concentrations in the cave fl owpath. Phosphate and sulfate decreased along the surface fl owpath, but increased slightly in the cave. This is reasonable considering there are natural sources of sulfate and phosphate in the limestone at Mammoth Cave National Park. Bacteria were cultured and evaluated for resistance to the microbicides called quaternary ammonia compounds (Figure 6). Soil-water bacteria collected near the White Nose Disinfection Stations and RV Dump Station had a much greater resistance to QACs than bacteria collected in pristine areas, indicating they are devloping antibiotic resistance. Specifi c conductance in fl owing cave waters ranged from 200-250 uS/cm. Storms had a temporary dilution eff ect on specifi c conductance in those same cave waters. An extreme storm that showered 2 inches in 24 hours caused the conductivity to Figure 4: TSU students installed instruments to monitor road runoff at Silent Grove. 180 Mammoth Cave National Park's 10th Research Symposium: Celebrating the Diversity of Research in the Mammoth Cave Region drop to 40 uS/cm. A pool perched in Gratz Avenue (in the cave) had a stable specifi c conductance of 315-335 uS/cm regardless of storms. These preliminary results help us to understand the current conditions in the cave prior to road salt treatment and how various chemical concentrations adjust along the fl owpath into the cave. Conclusions This partnership between Mammoth Cave National Park, U.S.G.S., Mammoth Cave International Center for Science and Learning, and, Tennessee State University to investigate water-quality in the Park had many positive outcomes. Some results were very tangible, such as, the monitoring results used to infl uence management decisions or document current ecosystem conditions. Results that were diffi cult to quantify include the benefi ts received by engineering and environmental students as they interacted and worked with professionals from the partnering institutions. Counting the vast number of student awards, presentations, and publications, or counting the number of internships, is one way to quantify the benefi ts of this project. But even that approach undervalues the results of this unique partnership. These monitoring activities helped to train the next generation of scientists and engineers and provided a very positive experience for all the participants.